1. Field of the Invention
This invention relates to the field of methods and apparatus for providing a triggering mechanism.
2. Background Art
There are a number of situations and circumstances that require the multiplication of a first force into a second force. For example, it may be necessary to transform a relatively weak force into a relatively strong force. It may also be necessary to transform a large force into a smaller force. Such applications require a "force transformer" to accomplish the desired transformation. The force transformer includes a triggering mechanism for receiving a first force of a first level and actuating a transformation means, transformation means, and actuating means for applying a second force of a second level.
A force transformer that converts a small force into a larger force is referred to as a "force multiplier". A force multiplier converts a received force of a first low level into an output force of a second higher level. In many cases, the applied low level force is used as a triggering force to activate the force multiplier. The force multiplier, when activated, provides a higher level actuating force to perform a desired function. An example of a force-multiplying system is the power steering system of an automobile, which transforms the relatively low force arm movements of a driver to more powerful forces for turning the wheels of the car.
Other applications for force multipliers include those that rely on atmospheric, hydrostatic, or mechanical pressure to trigger the application of a large force. One such application involves the flotation, marking, and retrieval of inadvertently-submerged objects to which the device is attached based upon actuation by hydrostatic pressure corresponding to a preselected depth.
Automatic flotation devices employing hydrostatic pressure-activated mechanisms for initiation of inflation of flotation elements from compressed gas sources have been proposed for the flotation, marking, and retrieval of inadvertently-submerged objects. Among such objects considered for flotation have been relatively small items, such as fishing rods and reels and firearms. Among those considered for marking and retrieval have been relatively larger items, such as outboard motors and boats.
Such devices typically consist of a pressure sensing means, a gas storage means, a gas release means that is responsive to the pressure sensing means, and a bladder or balloon that is inflated with the released gas to provide buoyancy, causing the balloon to float to the surface, marking the position of the submerged object or lifting the submerged object to at or near the surface.
A common drawback in the designs of the various mechanisms proposed for such flotation, marking, and retrieval has been the size or the mechanical inefficiency of their actuation mechanisms. Initiation of the inflation sequence in any compressed gas device involves piercing a metal seal on the gas container supplying the inflation gas. The piercing of the seal requires, typically, a relatively high pre-loaded spring force to drive the piercing implement through the seal. Because the spring-loaded piercing mechanism must be restrained from moving before actuation by a force equal to that to which it has been loaded, a significant force is required at actuation to overcome the friction inherent in the restraining mechanism. Because the actuation force in a hydrostatically-activated apparatus is derived from its pressure-responsive diaphragm, and because the level of that force is directly related to the surface area of its diaphragm, the relatively high actuation forces required in compressed gas devices have caused such apparati to be of impractically or undesirably large size in order to ensure reliable actuation.
Prior art devices intended for the flotation of inadvertently-submerged objects and based upon hydrostatic actuation of inflation of flotation elements with compressed gas are described in U.S. patents to Bannister, U.S. Pat. No. 2,687,541, and to Smith, U.S. Pat. No. 2,853,724. The Bannister patent utilizes the mechanical advantage of a wedge design to spread the legs of a spring catch to trigger a spring-loaded piercing mechanism. The Smith patent employs an overcenter lever trigger design to the same effect. These prior art devices do not provide efficient gain in the force multiplier component. That is the amount by which the force is multiplied is relatively small. As a result, the prior art devices are large, and not suited for applications where small size is a requirement. For example, a device for retrieving keys that are dropped into water should be small, so that a user can be comfortable carrying it. The prior art devices are not suitable for that application.